Insufficient information is available to determine rational environmental sulfate exposure standards that avoid toxic effects on lung function in normal human subjects and patients with cardio-pulmonary disorders. Overly lax standards will lead to adverse health effects while too stringent standards result in wasteful expenditures by industry and governmental agencies. We have constructed a controlled environmental chamber that can accurately deliver sulfate and sulfuric acid aerosols of known concentration and size to human subjects for periods as long as 48 hours. Location in an in-patient area of a large teaching hospital permits for the first time extension of planned initial studies in normal subjects to patients with diseases such as asthma, chronic bronchitis, and pulmonary emphysema. Alterations in lung function will be detected by pulmonary function tests (specific airway conductance, forced expiratory flow rates at low lung volumes) that have sufficient sensitivity to detect changes in lung function before symptoms occur. We will also use a previously developed quantitative bronchial challenge technique using an aerosol of carbachol to assess inherent airway reactivity that can detect subliminal actions of pollutants. In dogs, we will develop another technique to detect asymptomatic alterations in lung function. We will measure with external counters the relative clearance rates of monodispersed radioactive aerosol of different solubilities and structures before and after exposure to potentially toxic agents such as sulfates and sulfuric acid aerosols. This data should permit measurements of alterations in alveolar-capillary and bronchial permeability. In addition to altering particulate concentration and length of exposure periods, we will also study at realistic environmental concentrations a variety of sulfate salts ((NH4)2SO4, NH4HSO4, NaHSO4, etc.), effects of temperature and humidity, and response to several particle sizes. Ammonia concentration on the subject's expired air will be measured and correlated with airway responses. Once the lowest concentrations of sulfate aerosols are identified that produce adverse effects on lung function in normal subjects, we will then extend studies to patient populations that may be particularly vulnerable to the effects of inhaled pollutants such as subjects with asthma, emphysema, chronic bronchitis, or normal individuals with acute respiratory infections.